View Compilation Error

0_0_6925255_32666.cpp: In function `int main()':
0_0_6925255_32666.cpp:5: error: `scanf' undeclared (first use this function)
0_0_6925255_32666.cpp:5: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6925255_32666.cpp:16: error: `abs' undeclared (first use this function)
0_0_6925255_32666.cpp:23: error: `printf' undeclared (first use this function)